1. Field of the Invention
The present invention relates to a lamp driving circuit; and, more particularly, to a lamp driving circuit to receive a feedback reference current for controlling a lamp output current from an inverter transformer.
2. Description of the Related Art
With development of display technology, an LCD(Liquid Crystal Display) has been increasingly widely used in a TV and a monitor. As for the LCD and a CRT(Cathode-Ray Tube) monitor, the LCD has advantages in that a longitudinal cross-section is slimmed and flicker is reduced.
The LCD needs a back-light unit for supplying a light source because it does not emit light spontaneously and the back-light unit has a fluorescent lamp which is driven with a high voltage.
Meanwhile, in order to drive the fluorescent lamp of the back-light unit, a lamp driving circuit including an inverter is used.
The lamp driving circuit may be formed of an SMPS(Switching Mode Power Supply) and two printed circuit boards, i.e., an IP(Integrated Power) board mounting the inverter and a balance board.
At this time, the same inch of IP board is commonly used for common use of products and if there are many manufacturers of the back-light units used for the same inch, lamp output currents may be different to maintain the same brightness according to the manufacturers.
Further, since the lamp output currents may be different due to difference in the number of lamps and difference in brightness among the same inch and back-light unit manufactures, it is needed to control the lamp output currents so as to prevent product failure.
Therefore, in order to control the lamp output currents, a current transformer has been used in the balance board without change of the IP board, which increases a material cost due to addition of parts and may cause quality problems.